This application claims Paris Convention priority of DE 101 43 991.1 filed Sep. 7, 2001 the complete disclosure of which is hereby incorporated by reference.
The invention concerns an X-ray analysis apparatus for investigating material samples having a device for automatic exchange of the samples which contains a sample table with depositing positions disposed in m lines, wherein the lines extend parallel to an x direction and mxe2x89xa72, and with a gripping device for precise removal of any desired sample from a depositing position and transferral into a transfer and/or measuring position and back to a depositing position, wherein the gripping device can be linearly displaced parallel to the x direction.
An X-ray analysis apparatus of this type is known e.g. from the company leaflet xe2x80x9cSPECTROMETRY SOLUTIONS; S4 EXPLORERxe2x80x9d, Bruker AXS Analytical X-Ray Systems GmbH, 2001.
This document describes in detail the functional principles of an arrangement of this type. Such X-ray analysis apparatus are suited for rapid, routine, and non-destructive analyses of the most different of sample material in laboratories and research institutes. X-ray fluorescence, X-ray diffractometry, or other X-ray analysis methods can be used for examining the material samples. The material samples may be massive solid bodies, powder, or liquid samples disposed in appropriate sample containers.
Analysis devices of this type are provided for routine, rapid examination of a large number of samples. For this reason, an automatic exchange device must be provided for transporting, within the device, each of a plurality of samples to be examined. The known devices comprise a sample table for receiving the samples which is immovably fixed in the apparatus as e.g. described in the above-cited company leaflet. This sample table has openings defining an mxc3x97n matrix for inserting the different samples or sample containers. These are filled manually with the different samples according to a plan determined by the user before starting a measuring series which subsequently runs automatically without further manual influence on the part of the user.
Towards this end, the X-ray analysis apparatus comprises a gripping device for precise removal of any desired sample from one of the depositing positions, transfer into a transfer or measuring position and return back into the depositing position. To be able to address all positions on the rigid, rectangular sample table, the gripping device drive mechanism must be relatively complicated. The gripping robot must be movable in both the x and y directions. Gripping operations with the robot arm also require a substantial amount of space in the vertical z direction.
Taken together, the gripping device and the sample table, immovably mounted in the apparatus, occupy a very large, cuboid three-dimensional volume within the X-ray analysis apparatus. Since the device should also be used for routine examinations at locations where space is often quite limited, convenient use of an arrangement of this type with its associated operating elements in a typical working location is frequently problematic.
In view of the above, it is the underlying purpose of the invention to introduce an X-ray analysis apparatus with the above-mentioned features having simple topological construction which requires considerably less space due to a considerably more compact construction thereby maintaining full relative mobility of the parts, wherein accessibility to depositing, transfer and measuring positions is not less than that of the conventional device.
This object is achieved in accordance with the invention in a surprisingly simple and also effective fashion in that the sample table can be moved linearly, independently of the gripping device and parallel to a y direction extending at an angle xcex1 with respect to the x direction for gripping samples from different lines, with the sample table being disposed parallel to the x-y plane.
In this manner, construction of an X-ray analysis apparatus of this type is facilitated using means which are technically easy to realize. The available space can be used much more economically and the required space in the upper region of the apparatus can be considerably reduced without having to reduce the number of sample table depositing positions which can be addressed relative to conventional devices. This is possible since the gripping robot of the inventive apparatus must no longer be moved in both the x and y directions but only in the x direction. The sample table can be linearly displaced in the y direction relative to the robot such that the gripper can address any desired depositing position.
In the inventive X-ray analysis apparatus, the angle is preferably xcex1≈90xc2x0. This minimizes the space required for the gripping device and sample table and matches them to the geometry of conventional housings.
A geometric construction of the inventive X-ray analysis apparatus is also preferred with which the x-y plane extends horizontally. This permits optimum utilization of gravity during the gripping process. Moreover, liquid samples can be easily processed without the danger of spilling.
In a particularly preferred embodiment of the inventive X-ray analysis apparatus, the depositing positions are disposed on the sample table in the form of a matrix. Selection of the depositing positions by the user is simple and the sample table can be provided with a clear arrangement of samples for inserting the samples according to a system provided by the user. Moreover, addressing of a matrix of this type by the control software for the automatic gripping device is particularly straightforward.
To facilitate operation and to stock further sample tables with samples should there be a large number of samples to be examined, the sample tables are usually constructed such that they can be easily introduced into the X-ray analysis apparatus and be detachably mounted. Several sample tables can be provided for a given apparatus, wherein only one of them is mounted in the apparatus for the next measuring sequence. As an alternative or supplement, the inventive X-ray analysis apparatus can be designed such that the samples are introduced individually via an opening from the outside to a certain location of the sample table defined as the input position and are further transported from that location by the gripping device to depositing positions predetermined by the user.
One embodiment of the inventive X-ray analysis apparatus is particularly preferred with which the device for automatic exchange of the samples is housed in a common housing with the X-ray analysis apparatus. This permits particularly advantageous utilization of the above-mentioned advantages of the reduced space required for the gripping device due to the considerably more compact arrangement as facilitated by possible separation of x and y motion.
A particularly preferred further development of this embodiment is characterized in that the common housing tapers relative to the y direction towards the top in the direction of a vertical z axis which extends perpendicular to the x-y plane, wherein the gripping device is disposed in the upper tapering part of the housing. This can only be achieved with the inventive arrangement since the inventive gripping robot is only displaced in the x and not in the y direction. The space saved in the y direction in the upper part of the device can be utilized e.g. to install a monitor which would otherwise take up valuable space at another location in the operating chamber.
A further particularly preferred embodiment of the inventive X-ray analysis apparatus is characterized in that at least some of the samples are surrounded by a sample holder in the peripheral direction, wherein the respective sample or a container holding the sample projects past the sample holder in the direction of a vertical z direction, perpendicular to the x-y plane, the gripping device being disposed on that side of the sample to surround the parts of the sample or of the container holding the sample which project past the sample holder in an operating position in the z direction and grasp the sample holder.
The samples or sample containers of an X-ray analysis apparatus of this type are usually dimensioned such that they terminate at the upper edge of the sample holder in the z direction (see e.g. DE 198 51 501 C1). The sample-sided part of the gripping device thereby abuts the upper edge of the sample and of the sample holder during the gripping process. The above embodiment of the invention facilitates processing of samples extended in the z direction, e.g. liquid containers. This simplifies the loading and unloading of a sample holder having such samples extended in the z direction. Moreover, a gripping system of this kind can also easily grip conventional samples. This embodiment of the invention can therefore be used universally for the most different kinds of samples. While conventional systems have required special solutions for samples extended in the z direction, the above embodiment of the invention permits standardization of a very simple sample holder and use thereof at minimum cost.
In a particularly preferred further development of this embodiment, the sample holder comprises one (or several) holding section(s) disposed adjacent to the bottom-sided end of the sample or of the sample container to engage behind the sample or the sample container in a plane which is parallel to the x-y plane and act as mechanical stop in the z direction for the sample or sample container. This further facilitates loading the sample holder with the sample to obtain a defined, final position in the z direction.
The sample holder usually surrounds the sample annularly, preferably circularly, on its side facing the gripping device during operation. The sample or the sample container can then either be inserted or pressed into the sample holder ring.
In a further development of the invention, the sample holder comprises several parallel rods extending in the z direction which surround the sample in the peripheral direction on its side facing the gripping device during operation. This facilitates centering of the sample and extension of the rods in the z direction also provides a certain flexibility for deflection in the x-y plane during insertion of the sample to prevent damage to the sample due to excessive loading when pressed into the sample holder.
In a complementary fashion, the gripping device can also comprise at least three parallel rods which are preferably distributed uniformly about the periphery of the sample to be held and which extend in the z direction.
In embodiments of the invention, the gripping device can be operated mechanically. Although a gripping robot of this type is simple and inexpensive to manufacture, it is not very compact and requires significant amounts of space. In particular, relatively large amounts of sideward space are usually required in the horizontal x-y plane for a mechanical gripping process. The depositing positions of the samples in these embodiments must consequently have corresponding mutual separations to ensure safe gripping of the samples in the sample holder without contacting neighboring samples.
Alternatively or additionally, the gripping device can be operated pneumatically, preferably through suctioning the sample holders by underpressure. A pneumatically actuated mechanical gripper is also possible with which the pneumatic gripping, suctioning process must be carried out only at locations with particularly little space. In this case, the pneumatic device may serve both parts of the gripping system.
In a further development of this embodiment, the gripping device comprises rod-shaped gripping elements disposed on the side of the sample (as in an above-mentioned embodiment), wherein at least some of the parallel rods extending in the z direction can define suction nozzles for suctioning parts of the sample holder. In any case, an arrangement of this type requires considerably less space than a mechanical gripping arrangement since the parallel rods must not deflect in the x-y plane during the gripping process but can be rigidly lowered onto the sample holder in the z direction from above.
Embodiments of the invention are particularly preferred with which the gripping device is operated magnetically. The production of a magnetic means of this type is usually more expensive than a mechanical means but can be designed much more compactly.
In most of these embodiments, the gripping device is an electromagnet which can be externally controlled with electrical currents for activating and deactivating the gripping process.
In other further developments of this embodiment, the gripping device can have permanent magnetic sections on its side facing the sample holder during operation. A magnetic gripping device of this type is somewhat less demanding than an electromagnet, however a device for mechanical displacement of the permanent magnetic sections in the z direction must be provided for separating the grasped sample when depositing into the respective target position.
In a particularly preferred further development of the invention, the sample holder is formed at least partially of magnetizable, preferably ferromagnetic material on its side facing the gripping device during operation such that attraction and gripping thereof by means of a magnetic gripping device is particularly simple.
Further advantages can be extracted from the drawings and the description. The features mentioned above and below can be used in accordance with the invention either individually or collectively in any arbitrary combination. The embodiments shown and described are not to be understood as exhaustive enumeration but rather have exemplary character for describing the invention.
The invention is shown in the drawings and is explained in more detail by means of embodiments.